Additive package and method of compounding resins therewith

ABSTRACT

A package to contain materials to be added to a resin formulation containing vinylic monomer comprises a thin-walled plastic envelope which is soluble in the resin formulation. Preferably the envelope is made of polystyrene film. The polystyrene envelope is formed from sheet stock over a hot mandrel by sliding a rigid container onto the mandrel over a sheet of flexible plastic film overlying the mandrel. The sheet of film is large enough to form a lining for the rigid container with flaps of the film protruding from the rigid container. After materials are placed inside the lined rigid container, the flaps are sealed to form an enclosed film package within the rigid container. Additive materials which would themselves dissolve or attack the plastic envelope may be carried in an inert vehicle and/or be coated with an inert coating material to protect the envelope during storage.

United States Patent [191 McVay ADDITIVE PACKAGE AND METHOD OFCOMPOUNDING RESINS THEREWITH [75] Inventor: Malcolm Scott C. McVay,Aurora,

Ohio

[73] Assignee: U.S. Chemicals and Plastics, Inc., a

division of Alco Standard Corporation, Canton, Ohio [22] Filed: Dec. 20,1971 211 App]. No.: 210,018.

Related U.S. Application Data [63] Continuation-impart of Ser. No.10,316, Feb. 10,

[111 3,784,005 Jan. 8, 1974 FOREIGN PATENTS OR APPLICATIONS 955,0794/1964 Great Britain 206/47 A Primary Examiner-William T. Dixson, Jr.

Attorney-James H. Tilberry et al.

ABSTRACT A package to contain materials to be added to a resinformulation containing vinylic monomer comprises a thin-walled plasticenvelope which is soluble in the resin formulation. Preferably theenvelope is made of polystyrene fih'n. The polystyrene envelope isformed from sheet stock over a hot mandrel by sliding a rigid containeronto the mandrel over a sheet of flexible plastic film overlying themandrel. The sheet of film is large enough to form a lining for therigid container with flaps of the film protruding from the rigidcontainer. After materials are placed inside the lined rigid container,the flaps are sealed to form an enclosed film package within the rigidcontainer. Additive materials which would themselves dissolve or attackthe plastic envelope may be carried in an inert vehicle 12 Claims, 8Drawing Figures ADDlTlVE PACKAGE AND METHOD OF COMPOUNDING RESINSTHEREWITH DISCLOSURE This application is a continuation-in-partapplication to my copending application Ser. No. 10,316, filed Feb. i

10, 1970, now abandoned.

This invention relates to the resin compounding art and moreparticularly to a package for holding ingrediems (additives) to be addedto a resin formulation, and v to a method of making such packages andcompounding resins therewith.

The invention is particularly applicable to compounding polyester resinsand most particularly, unsaturated polyester resins, where styrene orsome other vinylic monomer is present for cross linking purposes.However, it will be appreciated that the invention is equally applicableto the compounding of any other resins which contain a vinylic monomer,and to the compounding of resin formulations which contain a componentin which the material from which the package envelope (as describedhereinbelow) is made, is soluble.

The term additive" as used in this specification and claims, is intendedto embrace any material which is added to a resin formulation, eg,materials which are added to the resin formulation to modify itsphysical and/or chemical properties, or to facilitate the molding CH CThe term vinyl(ic) monomer means a monomer or other polymer precursorwhich has the characteristic vinylic structure.

oxide will vary depending on the amount of settling which has takenplace, and whether the measured amount is taken from the top or thebottom of the bulk container. In any event, this procedure makes itexceedingly difficult to maintain a close control over the amount ofperoxide catalyst which is added to a given batch of polyester resin.

Another problem not coped with by automated measuring equipment is thehandling of hygroscopic additives. These may include CaO, Ca(OH) MgO andMg(Ol-l) which are useful as viscosity control agents.

Moisture picked up by these materials not only interferes with accurateweighings but also causes caking which makes it difficult to uniformlydistribute the materials throughout the resin.

One approach for solving the foregoing problems is to pre-package theadditive in a sealed container which is soluble in the resinformulation. Such a scheme is shown, for example, in British Pat. No.955,079 published Apr. 15, 1964. This patent discloses the use of asealed container made at least in part of polystyrene,

which contains a catalyst material. The polystyrene is of such athickness that when placed into a styrene containing resin formulation,at least the polystyrene portion of the package can dissolve in thestyrene and/or can be attacked by the catalyst composition itself sothat the catalyst material is liberated from the package into theformulation. There are some obvious short- 'comings to this scheme. [fthe polystyrene container is attacked by the additive it contains, i.e.,the peroxide 4O catalyst, its shelf life will obviously be very limited.The

The term copolymer as used in this specification and claims has itsusual meaning as being a polymeric material which combines two or moredifferent monomers in the polymeric molecular structure.

Heretofore, compounding of resins has been accomplished by maintainingbulk quantities of the additives on hand, measuring out the desiredquantity of additive from a bulk reservoir, and then blending themeasured amount of additive with the polyester resin.

This procedure suffers from a number of disadvantages. It requires theresin compounder to maintain on his premises bulk quantities of avariety of additives. The potential for error in measurement existseverytime a portion must be taken from the bulk additive and introducedinto the formulation. Additives with short shelflives may deterioratebefore they can be sed. The spillage of additives which may occur duringmeasurement and transfer of the additive to the resin is not onlywasteful and costly. but may result in inaccurate quantities ofadditives being introduced and consequent failure to meetspecifications.

Many of the foregoing problems can be coped with by the use ofsemi-automatic or fully-automatic measuring equipment, although this isan expensive solupatentee of the British Patent attempts to overcomethis problem by providing a composite container wherein only the upperportion is made of styrene and the lower portion is made of an inertmaterial or a material impervious to attack by the catalyst. In thismanner, when the container is up-ended into the resin formulation, thepolystyrene portion is dissolved. The patentee states that is is asimple matter to remove the remaining portion of the container from theformulation. However, it is obviously highly disadvantageous to haveinsoluble remnants of the package immersed in the resin formulation. Theformulation may have to be stirred or mixed, and it will be difficultand time consuming to remove the remnants, particularly if the remnantportions have been broken up into numerous pieces. Further, theintroduction of insoluble, extraneous material into resin formulation isoften unacceptable, since resins must often be compounded to exceedinglystrict specifications if they are to fulfill successfully their intendedfunction.

Another obvious shortcoming of the composite package approach of theBritish Patent is that if the package is jostled during shipment orstorage, the catalyst or other material contained therein will contactthe polystyrene portion and will commence to dissolve it.

I When the additive material is one which does not attack polystyrene,the Manly British patent teaches the use of an all-polystyrene package.However, in order to have a package of sufficient strength to be filled,sealed, handled and placed in storage, the wall thickness ofpolystyrene. required is such that the package would dissolve onlyslowly, particularly informulations which contain only a small portionof vinyl monomer or other substance in which the polystyrene is soluble.For example, in the Manly British patent referred to above, apolystyrene package of 0.3 mm wall thickness is sealed onto thecontainer by an adhesive or by heatfound in the end-sealing caps wouldremainundissolved. Further, the sealing with adhesive or by heatsealingis obviously a painstaking and time-consuming manufacturing operation.

For example, one previous procedure tried by applicant had been toemploy circular lids of five to 6' milsthick polystyrene and to form acylinder from 136 thick polystyrene by gluing the seam with apolystyrene adhesive. Thecylinder thus formed was glued to one circularlid to form a container open at one end, which was then filled with theadditive, and a second closing lid was then glued on the top end of thecontainer to seal it. This procedure was found to be time-consuming andlaborious. Also, the thicklid portions were difficult to dissolve in theresin formulation, and the thin center portion lacked sufficientmechanicalstrength to withstand handling in storage and use.

The foregoing discussion is in no way intended to deprecate the teachingof the-Manly patent, but merely to point out the prior art problemswhich the present invention is intended to overcome.

Another possible approach to the problem of prepackaged additives wouldbe to form a rigid allpolystyrene container from a foamed polystyrenematerial which, because of its low density, would contain less materialper unit wall thickness as'compared to sheet polystyrene. Theoretically,such material would than about two mils thickness is satisfactoryinsofar as solubility is concerned.

Although the thin film envelope ofthe invention overcomes the problem ofrapid and complete solution of the envelope in the resin formulation,certain problems were engendered by the thin-film construction.

For one, difficulty was experienced in forming, filling accordance withthe invention by filling and forming the envelope in its own rigidshipping and storage container, from which it is removed only at thepoint of use.

In accordance with the present invention, there is provided an additivepackage comprising an envelope made of a thin film of synthetic organicpolymeric material which is soluble in at least one component of theresinformulation into which the additive is to be introduced, the thinfilm envelope being formed in and supported by a rigid shipping andstorage container.

The invention is applicable to any resin formulation which contains oneor more components in which the thin film of organic polymeric materialwill dissolve, i.e., one or more solvent components. The term solventcomponent is used in some of the claims to mean dissolve more readilythan an equivalent thickenss of non-foam stock. However, even therelativey large surface area of polystyrene foam material does notpermit it to dissolve quickly enough, particularly in resin mixtures'where the component in which the foam material is soluble is present inbut limited amountsThe result is that undissolved pieces of the foammaterial remain in the resin formulation. Thus, foam material suffersfrom the same disadvantage as thick-wall plasticsheets.

It is accordingly an object of the present invention to provide. anadditive package which overcomes the foregoing problems and provides anair-tight soluble package of unlimited shelf life, which is simple andeasy to manufacture and which will completely dissolve in a short timeeven in resin'formulatins containing only a small proportion ofcomponents in which the plastic film is soluble.

In seeking tosovercome the problem of solubility, it was found that bymaking an additive envelope of a sufficiently thin film of syntheticorganic material, i.e., a thin'plastic film, the envelope would readilydissolve in the formulation, even if the formulation contained only aminor amount of component in which the film was soluble. Generally, itwas found that a film of not more the component of the formulation whichwill dissolve the film. For example, film materials such as polystyrenewill dissolve in aromatic compounds (unsaturated cyclic compounds), innaphthenic oils and solvents (cycloparaffins) and in esters. Polystyreneand other polymers of vinyl monomers (to the extent they can be formedinto self-supporting thin films) such as vinyl to]- uene, methylmethacrylate, alpha-methyl styrene, diallyl phthalate, triallylcyanurate, and methyl acrylate, are soluble in resin formulationscontaining vinylic monomers.

Therefore, in accordance with one aspect of the invention, there isprovided an additive package useful in compounding resin formulationswhich contain one or more vinyl monomers, comprising an envelope'formedof a thin, flexible sheet of organic polymericmaterial which is solublein the vinyl monomer, the envelope containing one or more additives, andbeing formed in and supported by a rigid shipping/storage container.

In accordance with another aspect of the present invention, there isprovided an additive package consisting of a thin flexible sheet ofsynthetic organic polymeric material which is soluble in vinyl monomerand which contains one or more additives, one or more of which additivesis reactive with the material from which the envelope is made, thereactive additives being coated with an inert substance and/or suspendedin an inert vehicle. Accordingly, the material from which the thinenvelope is made is protected from attack by the reactive additivescontained therein and enjoys a long shelf life.

In accordance with a more limited aspect of the present invention, thereis provided a method of manufacturing an additive package from a thin,flexible sheet of organic polymeric material, i.e., a plastic film whichcomprises placing a piece of film over a mandrel, sliding a rigidcontainer over the film and onto the mandrel so that the film is formedand folded into a lining for the rigid container, i.e., the filmsubstantially conforms to the interior surface of the rigid container.The film is of a size so that it protrudes beyond the end of the rigidcontainer. The additives are placed in the lined container, and theprotruding portions thereof are sealed by closing and sealing theprotruding ends thereof. The rigid container may then be capped. Themandrel may be, and preferably, is heated to an elevated tempera ture,i.e., to above room temperature, to aid in forming and folding the filminto the desired shape. When the film material is polystyrene, anelevated temperature of between about 180 F to 220 F, preferably about190 F to 210 F, of the mandrel outer surface is preferred.

The package in accordance with the invention thus comprises an envelopeformed of a thin film of plastic material within a rigid, supportingcontainer. Preferably, the film is not more than about two mils inthickness. The most preferred material of the invention is polystyrenefilm of about one mil in thickness; a preferred range of film thicknessis between about one and about 1.5 mils in thickness, although anythickness of film up to and including about 2 mils is suitable.Generally, the thinner the film is, the more quickly it will dissolve inthe resin formulation, but the more likely it is to be broken duringpackaging or storing and handling. A film thickness of about 1 mil hasbeen found to be the most desirable compromise between quick solubilityand sufficient mechanical strength. Ordinarily, a film of one mil oreven 2 mils thickness would not have sufficient mechanical strength towithstand packaging and handling, but when made and used in accordancewith the invention, such films have been found to be of suitablemechanical strength.

In accordance with the invention, the additive envelope is prepared byplacing a sheet of filmover a mandrel of suitable shape and sliding arigid container, the inner surface of which is complementary, i.e.,substantially conforms to, the outer surface of the mandrel, over thefilm and onto the mandrel. The interior of the rigid container obviouslymust be slightly larger than the outside dimension of the mandrel withthe formed, folded film around it. The fit of the container over themandrel is snug enough, however, to form the film into asurface-clinging lining of the container. Accordingly, the film must beof a sufficient size so that upon being formed and folded between themandrel and the container, it lines and clings to the entire insidesurface of the container, and extends for a sufficient distance beyondthe open end of the container to provide a flap for sealing.

The invention will be described in detail in connection with a preferredembodiment thereof, which is illustrated in the attached drawingswherein:

FIGS; 1A through 1F show schematically the sequence of assembling anadditive package in accordance with the invention;

FIG. 2 shows a partial section view of a package in accordance with theinvention; and

FIG. 3 shows schematically the use of an additive package in accordancewith the invention.

Referring now to FIG. l-A, there is shown an electrically heatedsubstantially cylindrically shaped mandrel supported on its base 12 andprovided with a lead 14 to a power source (not shown), and a control 16to adjust the surface temperature of the mandrellO.

A sheet of thin plastic film 20, preferably one mill thick polystyrene,is held in place substantially centered over the mandrel. A rigidcontainer 22, the inner surface of which substantially conforms to theouter surface of mandrel 10, is slipped onto madrel 10 and over film 20,as shown in FIG. 1B.

As shown in FIG. l-C, container 22 is .pushed all the way down ontomandrel 10 until the closed end 22-A of container 22 meets the upperhorizontal surface of mandrel 10. Sheet 20 is seen to be large enough sothat a folded portion thereof extends beyond the end of container 22 fora distance sufficient to provide a sealing flap for the finishedenvelope.

At this point, additive material is placed inside the film envelope asshown in FIG. l-D, wherein a feed hopper 24 introduces a measuredquantity of additive into the envelope. Actually, a number of differentadditives may be combined in the envelope. After filling, the protrudingflaps of film are sealed, as shown in FIG. 1E, by any suitable means,shown schematically as a heat sealer 23. Obviously, any suitable means,such as twisting or folding, heat sealing, employing an adhesive, or atie cord, etc., may be used to seal the envelope.

Finally, a lid 26 is placed over container 22 (FIG. l-F) to complete theshipping and storage and container. Shipping labels, identifying, and/orinstruction labels, etc., shown as item 25 may of course be applied.

It will be observed that the thin film package is formed by its rigidshipping and storage container, and is at all times from the moment ofbeing formed, protected and supported by the rigid container.Accordingly, the very thin sheet of plastic is able to withstand thefilling operation and the handling in shipment and storage withoutrupturing. Even if a small rupture should occur in the film, a drymaterial will substantially be held in place within the container by thetight fit between the rigid container and the film. By using a rigidcontainer made of or lined with a liquid-resistant material, evena leakin the envelope of a liquid additive presents no great problem.-Normally, a simple cardboard construction of the rigid container willsuffice, because rupture of the thin film material is prevented by thesupport of the rigid container 22. This is shown in FIG. 2, where evenif a rupture should appear in the film, significant leakage through thefilm is precluded by the back-up provided by the inner surface ofcontainer 22. At any event, being fully supported at all points by thecontainer, the likelihood of a rupture in the film is remote. Ifdesired, cap 26 may be sealed to container 22 by any suitable means, forstorage and shipment.

When the package is to be used, as shown in FIG. 3, lid 26 is removedfrom container 22, and container 22 is simply tip-ended over mixing vat30, which contains the resin formulation. Envelope 20 with its contentof additives slides out of container 22 and falls into the resinformulation. Envelope 20, being made of an extremely thin material, notmore than two mils in thickness, readily dissolves in the resinformulation, even if the formulation contains only a minor amount ofmaterial which will serve as a solvent for the material of envelope 20.Container 22 and lid 26 may be discarded or reused as desired.

In accordance with another aspect of the present invention, there isprovided, in a method of compounding a resin containing a solventcomponent with at least one additive, the steps of introducing into theresin a measured amount of at least one additive contained in anenvelope formed of a thin sheet of synthetic, organic polymeric materialwhich is soluble in the vinyl monomer, and admixing the resin, and theenvelope with its contents, until the entire envelope dissolves in thesolvent component and the additive is substantially uniformly dispersedthroughout the resin. Preferably, the solvent component is one or morevinylic monomers.

It is therefore, an object of the invention to provide an additivepackage for use in compounding resins.

A further object of the invention is to provide an additive packagecomprising an envelope formed of a thin sheet synthetic organicpolymeric material for use in compounding a resin containing a solventcomponent, in which the envelope is soluble.

A further object of the invention is to provide an additive packagewhich may be used simultaneously to incorporate a plurality of additivesin a resin.

Another object of the invention is to provide an additive. packagecontaining one or more additives which are reactive with the material ofthe package, and yet has a good shelf life.

Another object of the invention is to provide a simple, efficient methodof manufacturing the filled envelope package.

Yet another object of the invention is to provide a method ofcompounding resin formulation, eg, a polyester resin containing asolvent component, eg, vinyl monomers, by-mixing with the resin anenvelope made of a thin sheet of material, eg, polystyrene film, solublein the solvent component, and containing at least one additive forthe'resin.

Additives which may be packaged and used in the compounding of resinsaccording to the present invention, include catalysts, colorants,ultraviolet stabilizers,

fillers, fibrous reinforcement materials, thixotropic agents, moldrelease agents and the like. It is preferable that the additive benon-reactive with the material from which the additive envelope isformed, but this is not essential, because in some instances it ispossible to coat a reactive additive with an inert temporary covering toprevent interaction of the additive with the material forming theenvelope. The temporary protective material should dissolve or otherwisedissipate when the additive package is admixed with the resin. Further,an additive which is reactive with the envelope material may bedispersed in a non-reactive vehicle such as mineral oil, whereby thereactive particles are coated with the oil and reaction between theenvelope and the reac.

tive particles is eliminated or at least substantially alleviated. Forexample, a peroxide catalyst, such as, benzoylperoxide or such ascyclohexanol peroxide may be made into a paste with a mineral oilvehicle rather than dissolved in a conventional carrier (eg, dibutylphthalate or tricresyl phthalate), which would itself attack theenvelope material.

The invention also contemplates an additive package which contains aplurality of additives. Where the additives are compatible andnon-reactive with each other, they may be admixed directly with eachother and placed in an envelope. In some instances the compatibilityof'additives obtains only when they are in a dry state. In this eventcare should be exercised to place dry additives in the envelope,evacuate air from the envelope if deemed necessary and then seal theenvelope, as by heat-sealing.

Where the additives to be combined in a single envelope interact witheach other, as for example many colorants will react with peroxidecatalysts, it is contemgle envelope.

The material from which the additive package envelope is formed shouldbe readily soluble in the in the solvent component present .in the resinsystem. When the solvent component is one or more vinyl monomers, then,as aforesaid, to the extent that these monomers polymerize, e.'g.,methyl acrylate and methyl methacrylate, to form self-supporting filmsor sheets which can then be dissolved in the monomers, theirpolymeriz'atesin thin sheet or film form may also serve as the materialforming the additive package envelope.

Present economics strongly favor polystyrene film as the syntheticorganic polymeric material for forming the additive package envelope.According to the preferred embodiment of the invention the polystyrenetakes the form of an oriented film, having a thickenss up to about 2mils and preferably between about 1 and LS mils.

Non-oriented film may also be used but to no particular advantage, andit is generally less readily available and more expensive than orientedfilm.

Where one or more of the additives to be packaged in accordance with thepresent invention are solids which would tend to dissolve or react withthe film package, a vehicle may be used which will coat the reactiveparticles so that these will not attack or dissolve the envelope. Thus,while tricresyl phosphate and phthalic esters such as butyl and dioctyl'phthalate'are used conventionally as vehicles for solid peroxidecatalysts, they cannot be used in the practice of the present inventionwith a polystyrene or other vinylic film, since they would almostimmediately dissolve the material from which the envelope is formed.

Consequently other, inert, vehicles must be selected,

and as a group, essentially aromatic-free oils are satis-' factory forthe purpose. These may be of animal, vegetable or mineral origin andeither a lubricating, plasticizing or drying type. Specific examplesinclude USP mineral oil, castor oil, linseed oil, coconut oil and thelike. Because of its complete freedom from aromatic and otherdeleterious compounds mineral oils are preferred as the inert vehicle.

The substitution of a mineral oil as a vehicle to carry the peroxidecatalyst does not adversely affect the properties of the finishedproduct, and the coating action of the mineral oil on the particlepermits the additive to be prepackaged in a thin film, e.g.,polystyrene, package in accordance with the invention. The suitabilityof the mineral oil vehicle is illustrated in the examples set forthbelow, as is the lack of adverse affect by introduction of the(dissolved) polystyrene film.

EXAMPLE 1 The following ingredients were admixed in the proportionsindicated:

INGREDIENT 72 Unsaturated polyester resin 0 Benzoyl peroxide paste (50%di octyl phthalate vehicle) 06 Black iron oxide 1 O Zinc stcarate l 2Asbestos floats 27.2 Calcium carbonate ill) 34 glass fibers 13.0 V.sisal fibers [0.0

a commercially available premix resin, (100240 manufactured byCommercial Resin Division of lnterplastic Corporation) based on maleicanhydride and dipropylene glycol, containing 25 wt vinyl tolucne.

The glass fibers were added last to minimize breakage.

A portion of the resin composition was placed in a mold cavity and aslab measuring approximately 0.1 inch in thickness was molded and curedat conventional pressure and temperature values.

EXAMPLE II The procedure described in EXamplgl was repeated with thefollowing changes:

USP mineral oil was substituted as the vehicle for the.

benzoyl peroxide and this ingredient together with the black iron oxidewere placed in an envelope consisting of mil thick oriented polystyrenefilm. The envelope together with its contents were admixed with theresin until the film dissolved in the vinyltoluene and the cat'- alystpaste and pigment were substantially uniformly dispersed throughout theresin.

A visual inspection of the specimens produced in accordance withExamples 1 aid II revealed no discernible differences.

The specimens were tested for flexural strength in accordance with ASTMD-790;- for impact strength in accordance with ASTM D-256;andforfluxural modulus in accordance with ASTM D-790. The results are recordedin Table 1 below:

TABLE 1 Physical Property Example I Example ll Flexural strength, avg.(psi) 10,806 11,734 lmpact strength (foot-lbs/inch of notch-Izod) 2.873.13 Flexural modulus (psi) 668,080 701,280

The foregoing data indicates that the dissolution of the polystyrene bagin the resin and the use of mineral oil as the vehicle for the catalystdid not have an adverse affect on the physical properties of themoldedspecimen.

EXAMPLE Ill The following ingredients were admixed in the proportionsindicated.

INGREDXENT Wt 7; Unsaturated polyester resin* 66 Benzoyl peroxide paste(50% di-octyl phthalate vehicle) 1.5 Clay (ASP 400) 30 Green pigmentdispersion 2.5

*a commercially available resin based on isophthalic acid and diethyleneglycol. believed to contain about 25 wt styrene.

A portion of the resin composition was placed in a mold cavity andmolded and cured at conventional pressure and temperature valees.

. EXAMPLE IV The procedure described in Example III was repeated withthe following changes.

USP Mineral oil was substituted as the vehicle for the benzoyl peroxideand the resulting paste was placed in an envelope consisting of a 5milthick polystyrene film. The envelope togetherwith its contents wereadmixed with the resin until the film dissolved in the styrene and thecatalyst paste was uniformly dispersed throughout the resin.

A visual inspection of the specimens produced in accordance withExamples Ill and IV revealed no discernible differences.

The specimens were tested for hardness (Barcol) and no significantdifference in values was found.

The present invention may be practiced advantageously with theincorporation of viscosity control agents or thickeners into resinsystems. These agents find utility in resin formulations designed forsheet molding, bulk molding and low profile applications. Conventionalviscosity control agents include CaO, Ca- (Ol-l) MgO and Mg(OH) As aforesaid, because of the hygroscopicity of these agents they aresomewhat difficult to weigh accurately since the proportion of grossweight attributable to water pickup will vary with the length of timethe material has been exposed to the atmosphere and the humidity in theatmosphere.

Further, since the pick-up of water tends to cause the materials tocake, it becomes difficult to uniformly distribute them throughout theresin. This problem is eliminated, in accordance with the presentiriyention, by accurately weighing the viscosity control agents when dryand maintaining them in a dry state by sealing them in the additivepackage envelope which serves as a very satisfactory vapor barrier.

Although the dissolution of the envelope in the compounded resin doesintroduce a contaminant, the quantity of polymeric material dissolved isso small that it has no discernible affect on the appearance of physicalproperties of the cured resin.

The invention is operative with any resin system containing a sufficientamount of solvent component to solubilize the additive package envelopewithin a reasonable period. The polyesters, i.e., those resins formed bythe reaction between a dibasic acid and a dihydroxy alcohols, whichcontain a vinyl monomer as a crosslinker, are particularly suitable.

The present invention contributes to the art an additive package usefulin compounding polyester resins and a method of compounding such resins.The invention has been described in connection with certain specificembodiments. It will be appreciated however, that modifications of thedisclosed invention will readily suggest themselves to those skilled inthe art upon reading this disclosure. For example, multiple envelopesformed within their own rigid containers may be packed into a largercontainer to prepare a set of additive packages. Also, the envelope andrigid container (and necessarily, the mandrel) may have other than acylindrical shape, e.g., the shape may be rectangular, ovoid or squarein cross section. It is intended to include all such modificationswithin the scope of the appended claims.

As employed in the appended claims the term nonreactive, when used todescribe an additive which is inert with respect to the envelope, isintended to embrace also reactive additives which have been treated asby being coated or dispersed in a non-reactive vehicle to render themnon-reactive relative to the envelope material.

What is claimed is:

l. A package for introducing additives to resin formulations containingat least one solvent component,

1 1 comprising a rigid container having a surface clinging lining formedon the inside thereof, said lining comprising a removable envelopeformed of a film of synthetic organic polymeric material not greaterthan about two mils thick, and soluble in said solvent component, and atleast one additive contained within said envelope, which additive isreactive with said organicpolymeric material and is coated with an inertsubstance.

2. The package of claim 1 wherein said solvent component is a vinylmonomer and wherein said film is selected from the class consisting ofpolymers and copolymers of one or more of the following: styrene, methylstyrene, binyl toluene, methyl methacrylate, diallyl phthalate, triallylcyanurate, and methyl acrylate.

3. The package of claim 1 wherein said solvent component is a vinylmonomer.

4. A package for introducing additives to polyester resin formulationscontaining at least one-solvent component, comprising a rigid containerhaving a surface clinging lining formed on the inside thereof, saidlining comprising a removable envelope formed of a film of syntheticorganic polymeric material not greater than about two mils thick, andsoluble in said solvent I an inert liquidvehicle,

5. The package of claim 4 wherein said additive fu rther includes acolorant for said polyester resin.

6. The package of claim 4 wherein said catalyst is benzoyl peroxide andsaid liquid vehicle is s substantially aromatic-free mineral oil.

7. The package of claim 1 wherein said additive includes a colorant forsaid resin.

8. A package for introducing additives to resin formulations containingat least one solvent component, comprising a rigid container having asurface clinging lining formed on the inside thereof, said liningcomprising a removable envelope formed of a film of synthetic organicpolymeric material not greater than about two mils thick, and soluble insaid solvent component, and at least one additive contained within saidenvelope, which additive is reactive with said organic polymericmaterial, and is suspended in an inert liquid vehicle.

4 9. The package of claim 8 wherein said inert vehicle is mineral oil. Ig

10. The package of claim 8 wherein said solvent component is one or morevinyl monomers.

11. The package of claim 8 wherein said solvent component is a'vinylmonomer.

12. The package of claim 8 wherein-said solvent component is a vinylmonomer and wherein said film is se- I lected from the class consistingof polymers and copolymers of one or more of the following: styrene,

methyl styrene, vinyl toluene, methyl methacrylate, di-

allyl phthalate, triallyl cyanurate, and methyl acrylate.

2. The package of claim 1 wherein said solvent component is a vinylmonomer and wherein said film is selected from the class consisting ofpolymers and copolymers of one or more of the following: styrene, methylstyrene, binyl toluene, methyl methacrylate, diallyl phthalate, triallylcyanurate, and methyl acrylate.
 3. The package of claim 1 wherein saidsolvent component is a vinyl monomer.
 4. A package for introducingadditives to polyester resin formulations containing at least onesolvent component, comprising a rigid container having a surface -clinging lining formed on the inside thereof, said lining comprising aremovable envelope formed of a film of synthetic organic polymericmaterial not greater than about two mils thick, and soluble in saidsolvent component, and at least one additive contained within saidenvelope, which additive includes a solid catalyst for said polyesterresin, said catalyst being dispersed in an inert liquid vehicle.
 5. Thepackage of claim 4 wherein said additive further includes a colorant forsaid polyester resin.
 6. The package of claim 4 wherein said catalyst isbenzoyl peroxide and said liquid vehicle is s substantiallyaromatic-free mineral oil.
 7. The package of claim 1 wherein saidadditive includes a colorant for said resin.
 8. A package forintroducing additives to resin formulations containing at least onesolvent component, comprising a rigid container having a surface -clinging lining formed on the inside thereof, said lining comprising aremovable envelope formed of a film of synthetic organic polymericmaterial not greater than about two mils thick, and soluble in saidsolvent component, and at least one additive contained within saidenvelope, which additive is reactive with said organic polymericmaterial, and is suspended in an inert liquid vehicle.
 9. The package ofclaim 8 wherein said inert vehicle is mineral oil.
 10. The package ofclaim 8 wherein said solvent component is one or more vinyl monomers.11. The package of claim 8 wherein said solvent component is a vinylmonomer.
 12. The package of claim 8 wherein said solvent component is avinyl monomer and wherein said film is selected from the classconsisting of polymers and copolymers of one or more of the following:styrene, methyl styrene, vinyl toluene, methyl methacrylate, diallylphthalate, triallyl cyanurate, and methyl acrylate.